Molding is a process by virtue of which a molded article can be formed from molding material. Various molded articles can be formed by using the molding process, such as an injection molding process. One example of a molded article that can be formed, for example, from polyethylene terephthalate (PET) material is a preform that is capable of being subsequently blown into a beverage container, such as, a bottle and the like.
A typical molding system includes an injection unit, a molding machine and a mold assembly. The injection unit can be of a reciprocating screw type or of a two-stage type. The molding machine includes inter alia a frame, a movable platen, a fixed platen and an actuator for moving the movable platen and to apply tonnage to the mold assembly arranged between the platens. The mold assembly includes inter alia a cold half and a hot half. The hot half is usually associated with one or more cavities (and, hence, also sometimes referred to by those of skill in the art as a “cavity half”), while the cold half is usually associated with one or more cores (and, hence, also sometimes referred to by those of skill in the art as a “core half”). The one or more cavities together with one or more cores define, in use, one or more molding cavities. The hot half can also be associated with a melt distribution system (also referred to sometimes by those of skill in the art as a “hot runner”) for melt distribution. The mold assembly can be associated with a number of additional components, such as neck rings, neck ring slides, ejector structures, wear pads, etc.
As an illustration, injection molding of PET material involves heating the PET material (ex. PET pellets, PEN powder, PLA, etc.) to a homogeneous molten state and injecting, under pressure, the so-melted PET material into the one or more molding cavities defined, at least in part, by the aforementioned one or more cavities and one or more cores mounted respectively on a cavity plate and a core plate of the mold assembly. The cavity plate and the core plate are urged together and are held together by clamp force, the clamp force being sufficient enough to keep the cavity and the core pieces together against the pressure of the injected PET material. The molding cavity has a shape that substantially corresponds to a final cold-state shape of the molded article to be molded. The so-injected PET material is then cooled to a temperature sufficient to enable ejection of the so-formed molded article from the mold. When cooled, the molded article shrinks inside of the molding cavity and, as such, when the cavity and core plates are urged apart, the molded article tends to remain associated with the core. Accordingly, by urging the core plate away from the cavity plate, the molded article can be demolded, i.e. ejected from the core piece. Ejection structures are known to assist in removing the molded articles from the core halves. Examples of the ejection structures include stripper plates, ejector pins, etc.
U.S. Pat. No. 6,309,208 issued to Kazmer, et al. on Oct. 30, 2001 discloses an injection molding machine having first and second nozzles for delivering melt material from a common manifold to one or more mold cavities, apparatus for controlling delivery of the melt material from the nozzles to the one or more mold cavities, each nozzle having an exit aperture communicating with a gate of a cavity of a mold and being associated with an actuator interconnected to a melt flow controller, the apparatus comprising: a sensor for sensing a selected condition of the melt material through at least one of the nozzles; and, an actuator controller interconnected to each actuator, at least one actuator controller comprising a computer interconnected to the sensor for receiving a signal representative of the selected condition sensed by the sensor, the computer including an algorithm utilizing a value corresponding to a signal received from the sensor as a variable for controlling operation of an actuator for the at least one nozzle.
U.S. Pat. No. 6,544,028 issued to Wright et al. on Apr. 8, 2003 discloses a mixer method and apparatus for use generally in injection molding machines is provided. The apparatus and method is generally comprised of a mixer insert that retains a mixing element that is sealingly inserted in the injection molding machine, for example a hot runner manifold. The mixing element reduces the melt imbalances in a flowing melt stream for the formation of improved molded parts.
U.S. Pat. No. 4,692,030 issued to Tauscher et al. on Sep. 8, 1987 discloses a static mixing device includes a tubular casing and at least one mixing element composed of individual webs which are secured in the wall of the casing. The webs are disposed in crossing relation to each other with a transverse spacing therebetween. The terminal ends of each web are secured within the wall of the casing by being shrink-fitted, soldered, welded or threaded.
U.S. Pat. No. 5,421,715 issued to Hofstetter et al. on Jun. 6, 1995 discloses an apparatus for the simultaneous production of preforms consisting of polyethylene terephthalate (PET) fed and distributed to a plurality of cavities. In order to reduce the occurrence of acetaldehyde formation in a cavity, for example, a heated distributor block used in the production of preforms of the PET material, the material flowing through a channel is subjected to additional turbulence. To this end, an element, preferably of metal, is installed in the channels, such element being provided with sets of radial spokes which are azimuthally offset in relation to each other in the axial direction. Besides inducing turbulence, such spokes act as homogenizing elements serving to diffuse heat over the cross section of the flowing process material.
U.S. Pat. No. 5,564,827 issued to Signer on Oct. 15, 1996 discloses a device for the homogenization of high-viscosity fluids comprises static mixing elements and possibly filter elements. These elements of the device are arranged in a sleeve along the sleeve axis. According to the invention the sleeve is composed of several parts; the elements of the device are monolithic structural members and all or a plurality of these structural members have flange-like or nose-like parts. With these parts the structural members engage so as to anchor in the sleeve region between sleeve parts and form, at the same time, parts of the sleeve. The device according to the invention is provided, for instance, as a mixing head in the nozzle of an injection molding machine or as a melt mixer of an extruder.
U.S. Pat. No. 5,941,637 issued to Maurer on Aug. 24, 1999 discloses a flow forming member for a polymer melt comprises an inlet point as well as an outlet point, a tubular channel connecting these points and a rod-like body arranged along the channel axis. At least one static mixing element is arranged in the channel, preferably at least two static mixing elements are arranged one after the other. The mixing elements have apertures for the accommodation of the rod-like body. A firm connection exists between the body and the mixing elements. A minimum gap is provided between the mixing elements and the channel wall which permits a displacement of the body in the channel or an insertion into the channel.
U.S. Pat. No. 4,201,482 issued to Imhauser et al. on May 6, 1980 discloses a mixing insert of solid material into which intersecting channels are drilled is particularly suitable for use as a static mixer for highly viscous liquids. The insert provides a high quality of mixing while withstanding pressure differences of more than 107 Pa along the mixer. If the insert is rotated, static and dynamic mixing properties are superimposed on each other in the mixer. Either forward transport of the materials or return for remixing can be particularly promoted according to the sense of rotation and form of the external channels, which must be partly open.
U.S. Pat. No. 6,503,438 issued to Beaumont et al. on Jan. 7, 2003 discloses a tool structure or tool insert has a runner system which includes at least one branching runner which branches in at least two directions forming at least a first pair of branch runners for receiving laminar flowing material for the formation of a product. Each branch runner is at a position in the runner system such that it receives material having significantly similar conditions from side-to-side of a bisecting plane of that runner which bisects the cross section of at least a portion of the length of that branch runner. This material also has dissimilar conditions from side-to-side of a perpendicular plane of each branch runner which is perpendicular to the bisecting plane of that runner with the perpendicular plane of each branch runner also bisecting the cross section of the same portion of the length of each branch runner that the bisecting plane bisects. A repositioner in the tool or tool insert repositions the dissimilar conditions of the laminar flowing material to preselected positions in circumferential directions around the center of the flow paths of each runner of each pair of branch runners. Each pair of branch runners is joined at a location on each runner of each pair which causes the flow from each of these runners to form a half of a joint stream of material which has conditions across its flow path that are significantly balanced from side-to-side of two perpendicular planes which bisect the flow path of the joint stream.
U.S. Pat. No. 6,382,946 issued to Beck et al. on May 7, 2002 discloses a multi-cavity coinjection mold and method for simultaneously producing a plurality of multi-layered articles comprising: a mold structure defining a plurality of mold cavities; a first supply source for supplying metered amounts of a first molding material; a second supply source for supplying metered amounts of a second molding material; a hot runner system in communication with the first and second supply sources for conveying the metered amounts of the first and the second materials separately to a region proximate each of the cavities; the region comprising having a pin controlled passage leading to proximate cavity by way of a gate having the same cross-section as the passage, the pin scavenging material from the passage and providing cavity packing.
European patent 0 546 554 published on Mar. 19, 1997 discloses a hot tip gated injection molding apparatus having a heated manifold to distribute melt to a number of spaced gates. An unheated sealing and conductive member is mounted directly between the heated manifold and the cooled cavity plate in alignment with each gate. The sealing and conductive member has an elongated hot tip shaft which is connected to extend centrally through the bore of an outer collar portion by a number of spaced spiral blades. The collar portion bridges an insulative air space between the hot manifold and cooled cavity plate to prevent melt leaking into it. Heat received through the rear end of the collar portion which abuts directly against the heated manifold is transferred through the blades and the hot tip shaft to the gate area which is aligned with the pointed forward end of the hot tip shaft. The rear end of the hot tip shaft extends rearwardly into a branch of the melt passage to pick up heat from the surrounding melt. The hot tip shaft has a highly conductive inner portion inside an abrasion resistant outer portion to conduct heat to and away from the gate area during different parts of the injection cycle. The spiral blades impart a swirling motion to the melt which flows between them.
U.S. Pat. No. 6,077,470 issued to Beaumont on Jun. 20, 2000 discloses a method of balancing the flow of a molten polymer containing material in a multi-runner injection mold includes the step of providing a mold body having at least one mold cavity and at least two runners. The first runner includes first and second ends and is connected to a source of molten material. The first runner is connected to a second runner. The second runner is connected to the at least one mold cavity. A stream of a molten polymer containing material flows through the first and second runners. The stream is repositioned in a circumferential direction as it flows from the first runner through the second runner while maintaining continuity between laminates of the stream of the molten material in a radial direction. In this way, a balance is provided for the melt temperatures and material properties of the cross branching runners. An apparatus for producing molded products having balanced thermal, material and flow properties includes a device for repositioning a stream of the molten polymer containing material as it flows from a first runner into at least a second downstream runner. If desired, the stream of molten thermoplastic material can be repositioned by approximately 90 degrees.
U.S. Pat. No. 7,198,400 issued to Unterlander et al. on Apr. 3, 2007 discloses a static mixer comprising a mixer body with a first and a second array of intermeshed and interconnecting passageways formed therein that connect, and provide a convoluted flow path between, flow faces at ends of the mixer body. The first and second arrays of passageways preferably interconnect such that the boundaries of adjacent intermeshed passageways overlap to form mixing portals. When used in an injection molding system, a singular melt flow is initially divided at the first flow face of the static mixer, wherein the melt flow divides into the intermeshing passageways and further divides and re-combines at the locations of mixing portals before exiting the static mixer at the second flow face as homogenized melt.
Japanese patent application 2003340896 assigned to Meiki Co LTD and published on Dec. 2, 2003 discloses aims to provide a method which does not need an external heater, directly heats a molten material, allows for injection-molding of a conductive thin wall article at a relatively low injection pressure, and improves the fluidity of the molten material during injection-packing and an apparatus for the method. To that extent there is provided a solution which involves, when the molten material in an injection molding machine for injection-molding the molten conductive material is heated, in a passage with a channel in a nozzle in which the molten material to be packed in a mold cavity flows expanded and formed, an electrode having a cross-sectional shape resembling that of the passage and an cross-sectional area smaller than that of the passage is suspended by terminals to form a uniform clearance between the passage and the electrode. Power is supplied from a power supply to the electrode and the nozzle through the terminals to heat the molten material by resistance heating.